1. Field of the Invention
The present invention relates to a traction sheave elevator.
2. Description of the Background Art
In prior art, specification EP 0 631 967 A2 presents a traction sheave elevator without machine room, in which an elevator car moving in an elevator shaft is guided by vertical car guide rails while the counterweight moves along guide rails placed on the same side of the elevator car as the car guide rails. Such a suspension arrangement, in which all guide rails are placed as a compact structure on one side of the elevator car, is called piggyback suspension. The drive motor, provided with a traction sheave, is mounted in the upper part of the guide rails. Connected to the elevator car are two car rope pulleys, placed under the bottom of the elevator car at opposite edges. The first end of the rope is attached to a fixed top structure in the upper part of the elevator shaft, on the same side of the elevator car as where the car and counterweight guide rails are located. From the anchorage of its first end, the rope is passed down via a counterweight rope pulley attached to the counterweight, from where it is deflected up and passed to the traction sheave of the drive motor, from where it is further deflected down and passed around two rope pulleys mounted on the elevator car, so that the rope passes under the elevator car by one side, where the guide rails are located, to the other side and further up to a fixed top structure, to which the other end of the rope is fixed and which is located on the other side of the elevator car relative to the location of the car and counterweight guide rails. In this way, an advantageous 2:1 suspension arrangement is achieved, allowing the machinery to be designed in accordance with a lower torque requirement.
A problem with the prior-art elevator is that the two rope pulleys below the elevator car require a certain space in the vertical direction of the elevator. This a problem particularly in buildings where it is not possible to extend the elevator shaft substantially below the level of the lowest floor to provide a sufficient space for the rope pulleys under the elevator car when the car is at the bottom floor. This problem is often encountered in conjunction with the modernization of old elevator shafts where a scanty space has been provided at the bottom end of the shaft. In old buildings, building a new elevator shaft or extending the old one to a level clearly below the bottom floor is a significant cost factor. Similarly, an insufficient head room at the top end may be an obstacle to mounting car rope pulleys on the top of the elevator car. As for new buildings, an elevator shaft that takes up as little space in the vertical direction as possible would be an advantage.
A further problem with the prior-art elevator is that, on the opposite side of the elevator car relative to the side on which the car and counterweight guide rails are located, a sufficient space for rope passage must be provided between the shaft wall and the wall of the elevator car, which constitutes a limitation of the widthwise dimension of the elevator car, preventing effective utilization of the cross-sectional area of the elevator shaft.
The object of the invention is to eliminate the problems mentioned above.
A specific object of the invention is to disclose an elevator that is as compact as possible, requiring as little space as possible in the elevator shaft in both vertical and horizontal directions so as to allow as efficient shaft space utilization as possible. A further object of the invention is to disclose an elevator which is well suited for use both in new buildings and in old buildings for the modernization of elevator solutions in existing elevator shafts or even as an elevator for which a shaft is built afterwards in an existing building.
The elevator of the invention comprises car guide rails disposed vertically in an elevator shaft; an elevator car designed to move along the car guide rails; counterweight guide rails disposed in the elevator shaft on the same side of the elevator car as the car guide rails; a counterweight designed to move along the counterweight guide rails; an upper rope pulley mounted on a fixed top structure in the upper part of the elevator shaft; a car rope pulley connected to the elevator car; a counterweight rope pulley connected to the counterweight; a drive motor disposed in the elevator shaft to drive one of the rope pulleys; and a rope whose first end is attached to a fixed top structure in the upper part of the elevator shaft on the same side of the elevator car with the car and counterweight guide rails, from where the rope is passed via the counterweight rope pulley, upper rope pulley and car rope pulley, and whose second end is attached to a fixed top structure.
According to the invention, the second end of the rope is attached to a fixed top structure on the same side of the elevator car as the first end. The car rope pulley is rotatably mounted with bearings at the side of the elevator car on the same side of the elevator car as the car and counterweight guide rails.
xe2x80x98Fixed top structurexe2x80x99 refers to a fixed structure in the upper part of the elevator shaft near the ceiling, or to the top of the elevator shaft, the guide rails in the upper part of the shaft or corresponding structures.
The invention has the advantage that it makes it possible to build an elevator that is as compact as possible in the vertical direction and, on the other hand, as large as possible in relation to the cross-sectional area of the elevator shaft. The entire machinery as well as the rope and rope pulleys can be located on one side of the elevator car as a compact package. Furthermore, the invention has the advantage that, in addition to new buildings, it is suited for use in modernization projects. A further advantage is that the space at the bottom end of the elevator shaft can be constructed to dimensions as small as possible. In addition, the invention has the advantage that it is suited for use as an elevator without machine room, with the elevator machine mounted in the elevator shaft.
In an embodiment of the elevator, the car guide rails and counterweight guide rails are attached to each other and to the wall of the elevator shaft, arranged side by side parallel to each other, the counterweight guide rails being placed between the wall of the elevator shaft and the car guide rails.
In an embodiment of the elevator, the distance between the counterweight guide rails is equal to the distance between the car guide rails. The conventional design of the counterweight is such that the mass of the counterweight equals the car weight when the car is empty, added by half the specified load. By disposing the counterweight guide rails at a maximal distance from each other, the width of the counterweight can be maximized, and consequently a compact counterweight with a short vertical dimension is achieved.
In an embodiment of the elevator, the upper rope pulley is the drive wheel connected to the drive motor. In this case, the drive motor is mounted on the car guide rails and/or counterweight guide rails in the upper part of the elevator shaft, which means that the elevator has no machine room. It is also possible to use one of the other rope pulleys mentioned as a drive wheel.
In an embodiment of the elevator, the elevator comprises an L-shaped frame structure attached to the car, extending on the side wall of the elevator car on that side where the car guide rails and counterweight guide rails are located and under the bottom of the elevator car. The car rope pulley and the guide elements acting together with the car guide rails are connected to this frame structure.
In an embodiment of the elevator, the car rope pulley is placed in the lower part of the elevator car near its bottom.
The car rope pulley is preferably disposed inside the space defined by the elevator car and the frame structure to achieve compact space utilization.
In an embodiment of the elevator, a vertical tangent to the upper rope pulley is substantially aligned with a vertical tangent to the counterweight rope pulley, in which case the rope portion between them is substantially vertical. Correspondingly, a vertical tangent to the upper rope pulley is substantially aligned with a vertical tangent to the car rope pulley, so the rope portion between these pulleys, too, is substantially vertical.
In an embodiment of the elevator, the middle plane of rotation of the counterweight rope pulley is parallel to the middle plane of rotation of the car rope pulley. The middle plane of rotation of the upper rope pulley is at an angle to the middle planes of rotation of the car rope pulley and counterweight rope pulley. In this case, the middle plane of rotation of the car rope pulley may be parallel to the side wall of the elevator car, or alternatively the middle plane of rotation of the car rope pulley may be at an angle to the side wall of the elevator car.
In an embodiment of the elevator, the drive motor is a permanent magnet synchronous motor and the upper rope pulley is integrated with the rotor of the motor.
In a traction sheave elevator without machine room, the use of a diverting pulley mounted on the side of the elevator car to suspend the car on the hoisting ropes allows the elevator to be installed in an elevator shaft having a height dimension smaller than the conventional height. In principle, this solution can be used both in elevators with machine room above and in elevators with machine room below. To economize on the cross-sectional area of the elevator shaft, the diverting pulley attached to the elevator car must be parallel to the car wall or only moderately askew relative to the wall. An economical solution is to mount the hoisting machine on a fixed structure of the elevator shaft. However, in elevators with machine room below, the amount of material including diverting pulleys and ropes is larger and, as the number of diverting pulleys and rope portions between rope pulleys is larger, a solution with machine room below may result in an elevator having a slightly larger height dimension than an elevator with machine room above. When the suspension of the elevator is implemented using a diverting pulley on the side of the elevator car, the height dimension can be best reduced by placing the drive machine at such a height in the elevator shaft that the elevator car can move to a position alongside the machine.